黄土塬区大气降水的氢氧稳定同位素特征及水汽来源  

Analysis of stable isotopic composition and vapor source of precipitation at the Changwu Loess Tableland

作　　者：陈曦[1] 李志[1,2] 程立平[3] 刘文兆[2] 王锐[4] 

机构地区：[1]西北农林科技大学资源环境学院,杨凌712100 [2]黄土高原土壤侵蚀与旱地农业国家重点实验室,杨凌712100 [3]平顶山学院资源与环境科学学院,平顶山467000 [4]河南理工大学测绘与国土信息工程学院,焦作454000

出　　处：《生态学报》2016年第1期98-106,共9页Acta Ecologica Sinica

基　　金：国家自然科学基金项目(51179161&41401015);陕西省科学技术研究发展计划项目(2013KJXX-18);中央高校基本科研业务费专项资金项目(2452015105)

摘　　要：降水是水资源的主要输入,分析其氢氧稳定同位素特征可为水循环研究提供重要的背景信息。基于4a的降水样品采集,测定和分析了黄土塬区降水氢氧同位素(2H,17O和18O)的组成特征,进而分析了其水汽来源。降水同位素有明显的年内变化,2—6月富集而7—11月贫化;δD和δ18O存在雨量效应和温度效应,分别出现在6—9月和10—5月;但这些组成特征受气候变异影响存在年际差异。综合分析降水方程线、D盈余和17O盈余,发现黄土塬区6—9月降水来自海洋性气团,10—5月降水是局地水汽蒸发和大陆性气团起主导作用;雨季少数降水事件直接来源于海洋性气团,其他降水事件则是海洋性气团经再分配相对湿度达90%左右时才产生。全年至少30%的降水事件经历了严重的二次蒸发。As important constituents of a water molecule, the stable hydrogen and oxygen isotopes are ideal conservative tracers for water source, and thus, have been widely used in water cycle research. Precipitation is the main input of water resources ; therefore, analysis of its hydrogen and oxygen isotopic compositions can provide basic information for water cycle. Until now, some research has been carried out for the arid and semi-arid regions on the Loess Plateau; however, few studies have focused on the semi-humid region. The Changwu Loess Tableland, which is located in the southern part of the central Loess Plateau and is characterized by a warm temperate, semi-humid, continental monsoon climate （annual mean precipitation is 578 mm） , has been studied. In this study, the hydrogen and oxygen isotopic compositions （2H, 18O and 17O） of precipitation and some climatic factors （temperature, precipitation amount, humidity） of four years （2005, 2010, 2012--2013） have been determined fort the investigation of the vapor source of precipitation. Both seasonal and inter- annual variations were detected from the isotopic compositions of the precipitation. The isotopic compositions were moredepleted from July to November, and the δ18O and δD varied from -12.42‰ to -9.96‰ and from -88.62‰ to -65.18‰, respectively; however, they were more enriched from February to June, and the ranges of 8180 and 8D were -7.89‰ to -5.08‰ and -50.08‰ to -27.90‰, respectively. The most abundant depleted isotopic compositions were observed in July, which was considered to be the effect of marine air mass and precipitation amount. 8D and 8180 had a significant relationship with the precipitation amount from June to September, and while they correlated well with air temperatures from October to May. The inter-annual variations in isotopic compositions of precipitation were mainly due to the climate variability; for example, the temperatures in the summer of 2005 were the highest since 1951, and it would, thus, yield d

关 键 词：大气降水 氢氧同位素 水汽来源 黄土塬区 17O盈余 

分 类 号：P426.612[天文地球—大气科学及气象学]